Lipases are important industrial enzymes which are widely used in many applications. One of the major obstacles for a still wider utilization is the production cost of lipase and several efforts have been made to increase the yield of lipases by optimization of the production steps.
Expression of lipases in cells is dependent on several regulatory sequences which are not part of the mature protein. One such regulator is a propeptide located when present N-terminally just before the sequence of the mature lipase. A few publications have described modifications in the propeptide of Rhizomucor miehei lipase:
CN102851263 (Fengyi Shanghai Biotech Res & Dev CT Co LTD) describes that the L57V (L-14V) mutant, and L57V (L-14V) mutants further comprising V67A (V-4A), S65A (S-6A) as well as mutations in the mature lipase showed increased activity.
CN102337253 (Zhejiang University) describes that mutants comprising the mutations D48V (D-23V), and/or V67A,D (V-4A,D) together with mutations in the mature lipase demonstrated improved activity and thermostability. The effect of mutations in the propeptide alone was not disclosed.
Wang, J., et al. 2012 Appl Microbiol Biotechnol vol 96: p 443-50 describes that mutants with the mutations: L57V, D64A, S65A and V67A in the propeptide showed an increase in activity (Kcat(min-1)) over the wildtype.
Lui, Y., et al. 2014 Curr Microbiol vol 68: p 186-91 describes that deglycosylation of the propeptide in N8A (N-63A) and N58A (N-13A) mutants exhibited a twofold higher activity as compared to the wildtype.
The challenge is to produce increased amounts of enzyme protein in an active form which also will function in the various applications such as in detergent compositions.
There is thus still a need for additional means for improving both the quantity as well as the quality lipase.